Various kinds of corticosteroids have recently been used as antirheumatic, anti-inflammatory, anti-allergic and antishock agents. Further, with respect to the administration route, they have recently become widely utilized externally as well as internally. These compounds includes those having a structure in which the corticosteroid is substituted by methyl, hydroxy, halogen(bromine, chlorine or fluorine), esterified hydroxy or acetonised hydroxy, and derivatives thereof. Accordingly, they have structures significantly modified or changed from structures of naturally occurring corticosteroids, such as, for example, triamcinolone, fluorocinolone acetonide, betamethasone, dexamethasone and their derivatives. Although these compounds are clinically effective, they tend to show side effects such as systemic action, and some therapeutists have been concerned about the side effects by the halogensubstituted structure. Furthermore, since each of these prior compounds has a structure considerably modified or changed from natural occurring corticosteroid structures, their mechanisms of metabolism and excretion in a living body are complicated. Accordingly, even if they are externally administered, they are not always safe.
Given such a background for these prior steroids, we have conducted research with a view to developing a steroid having a structure similar to that of a naturally occurring corticosteroid, and showing an excellent anti-inflammatory action on topical administration. As a result, we have found that 17.alpha.-butyryloxy-11.beta.-hydroxy-21-propionyloxy-4-pregnen-3,20-dione , i.e., hydrocortisone 17-butyrate 21-propionate, has a much higher optical anti-inflammatory activity than other hydrocortisone derivatives and the commercially available steroidal agents for external administration.